Apparatus for sensing vehicles

Abstract

An underground vehicle sensing system extends below a vehicle travel surface to detect the presence of a vehicle. A conduit extends substantially horizontally underground from an access hole placed at the side of the vehicle travel surface. A plurality of sensors are spaced apart in the conduit to detect localized changes in the magnetic field. A plurality of sections house the probes and wiring to orient and position the probes. Sections detachably clip together to form a lightweight support structure and may be added one by one through the access hole. Lightweight extension members are utilized in some configurations between the support sections for positioning and supporting the probes.

What is claimed is: 
     
       1. A system for detecting vehicles on a vehicle travel surface, comprising: (a) a conduit for installation under the vehicle travel surface; and   (b) a support section adapted for insertion and sliding within the conduit, said support section arranged to carry a sensor probe at a fixed orientation relative to the support section to a predetermined position within the conduit, a second support section connected to said support section in an end to end manner by an attachment structure, the support sections adapted for rotation together within the conduit even after complete installation to permit adjustment of the orientation of the sensor probe with respect to the vehicle surface, such that the support section can be accessed without damage to the vehicle travel surface.   
     
     
       2. A system according to claim 1, wherein each support section is separable from each adjacent support section. 
     
     
       3. A system according to claim 1, further comprising at least one clip for detachably connecting adjacent support sections to each other. 
     
     
       4. A system according to claim 1, wherein the system further comprises a sensor probe within the support section. 
     
     
       5. A system according to claim 4, wherein said sensor probe is wired to a remote indicator. 
     
     
       6. A system according to claim 1, further comprising an insertion portion including an access hole connected to the conduit. 
     
     
       7. A system according to claim 6, further comprising a cradle connected to a first end of the conduit within the access hole. 
     
     
       8. A system according to claim 1, wherein the system includes a support section with a frustro-conical end portion. 
     
     
       9. A system according to claim 1, wherein the system includes a support section that is weighted to orient that support section. 
     
     
       10. A system according to claim 1, wherein the conduit is installed beneath or within the vehicle travel surface. 
     
     
       11. A system according to claim 10, wherein the conduit is placed between 40 and 60 centimeters below the vehicle travel surface. 
     
     
       12. A system according to claim 1, further comprising spacers for insertion intermediate said support section and an adjacent support section for connecting the selected support sections at a fixed position relative to each other. 
     
     
       13. A system according to claim 1, wherein each support section has a plurality of sensor probe mounting locations. 
     
     
       14. A support section for a probe, comprising: (a) outer walls;   (b) a receiving portion for receiving the probe; wherein the receiving portion is configured for maintaining the probe in a fixed position relative to the support section;   (c) a mounting portion; and   (d) an attachment structure adjacent an end of the support section, the attachment structure being attachable to a mounting portion of an adjacent support section and, when so attached, both support sections may be rotated together within a conduit to permit adjustment of the orientation of the probe even after complete installation without damage to the vehicle travel surface, wherein both support sections are adapted for insertion and sliding within the conduit.   
     
     
       15. The support section according to claim 14, wherein the mounting portion is a tab, and the attachment structure is a slot for receiving the tab. 
     
     
       16. A support section according to claim 14, wherein the receiving portion is configured for aligning the probes toward an open top portion. 
     
     
       17. A method for installing an underground vehicle sensing system for sensing the presence of a vehicle on a vehicle travel surface, comprising the steps of: (a) forming an access hole and providing a conduit extending from the access hole substantially horizontally below the vehicle travel surface;   (b) inserting a support section into the access hole and mounting a sensor probe in the support section;   (c) moving the support section and the sensor probe into the conduit so that the access hole may receive another support section;   (d) inserting the another support section into the access hole and attaching it to a previously inserted support section;   (e) mounting a sensor probe in the another support section;   (f) moving the support sections into the conduit until said sensors are located at predetermined locations below the vehicle travel surface; and   (g) rotating the support sections as a unit to provide the sensor probes at a desired orientation.   
     
     
       18. A method according to claim 17, wherein the access hole is formed remote from the vehicle travel surface. 
     
     
       19. A method according to claim 17, wherein the support sections are placed in a cradle having an open top prior to moving into the bore.